Tonight I gave myself a few minutes to take this app for a drive and check out its accuracy. Basically, this app uses GPS to calculate your current speed, then display it using a number of different analog readouts. There’s also a digital readout which you can change the color on, if you choose to go that way.

Other than using your iPhone to check your speed, something that I’m sure your speedometer will already be showing you, this app does have another useful feature: speed warning. Basically, the premise here is that you set the app to warn you once you cross a certain speed. Kind of like keeping you honest on your commute, providing you actually get the chance to speed during your congested commute.

Another function of the app, which would work well if the screen was brighter, is the HUD mode or “Heads Up Display.” Enabling this mode causes the display on the iPhone to be mirrored. You then place the phone on your dashboard and you should be able to see the reflection of the display on the windshield. There’s only one problem, if it isn’t dark outside this mode is useless. Also, we found that even with the headlights on it was also too bright (outside) to really see the reflection. We could position the phone to get a good reflection, but it just wasn’t practical. However, had the iPhone had a brighter display this may have likely worked a lot better.

We found the app to be exactly accurate for showing us our current speed. However, since the app has to calculate your speed based on GPS points, it will lag behind during periods of accelleration or deceleration. Once your speed is steady the app will be accurate in its speed calculation.